Converting the resolution of an image using interpolation and displaying the converted image

ABSTRACT

An apparatus, method, system, computer program and product, each capable of converting a resolution of an image using an interpolation method. The interpolation method determines a pixel value of an interpolated pixel based on a weighting factor, which is generated based on a pixel value and a distance value of a reference pixel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to Japanese patent applicationNos. 2004-206408 filed on Jul. 13, 2004, and 2005-039603 filed on Feb.16, 2005, in the Japanese Patent Office, the entire contents of whichare hereby incorporated by reference.

FIELD OF THE INVENTION

The following disclosure relates generally to converting the resolutionof an image using interpolation and displaying the converted image.

DESCRIPTION OF THE RELATED ART

The existing display apparatus is usually provided with a function forconverting the resolution of an image. For example, if the image has aresolution lower than an output resolution of the display apparatus, theresolution of the image may be increased using any one of the knowninterpolation methods, including the nearest neighbor method, linearinterpolation method, or cubic convolution method, for example. Inaddition, various interpolation methods have been recently introduced,as described in the Japanese Patent No. 2796900 (“the '900 patent”),patented on Jul. 3, 1998, for example.

The nearest neighbor method can be processed at a high speed, however,it may generate jaggedness in the image. The linear interpolation methodmay be more effective than the nearest neighbor method for generating asmoother image, however, it may lower the sharpness of the image, thuscreating a blurred image. The cubic convolution method can providehigher image quality, as compared with the nearest neighbor method orthe linear interpolation method, however, it requires a large referencerange, thus making calculation more complicated. Further, the cubicconvolution method may enhance a noise component of the image. Themethod disclosed in the '900 patent can provide higher image quality ascompared with the nearest neighbor method with a relatively smallerreference range, however, the image still suffers from jaggedness.

As described above, none of the known methods can generate an image,which is smooth and sharp, without enhancing jaggedness in the image.Further, none of the known methods can generate a high quality imagewhile suppressing a computation amount.

BRIEF SUMMARY OF THE INVENTION

An exemplary embodiment of the present invention includes an apparatus,method, system, computer program and product, each capable of convertingthe resolution of an image using a first interpolation method, themethod comprising the steps of: specifying an interpolated pixel to beadded to the image; selecting a plurality of reference pixels from avicinity of the interpolated pixel; obtaining a distance value for eachof the reference pixels; extracting a pixel value for each of thereference pixels; generating a weighting factor for a target referencepixel selected from the plurality of reference pixels using the distancevalue and the pixel value of the target reference pixel; and adding theinterpolated pixel having a pixel value determined by the weightingfactor of the target reference pixel.

Another exemplary embodiment of the present invention includes anapparatus, method, system, computer program and product, each capable ofconverting a resolution of an image using an interpolation method, whichis selected from a plurality of interpolation methods including thefirst interpolation method according to characteristics of the image.

Another exemplary embodiment of the present invention includes anapparatus, method, system, computer program and product, each capable ofdisplaying an image having the resolution converted by using the firstinterpolation method or the selected interpolating method.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic block diagram illustrating a structure of an imagedisplay apparatus according to an exemplary embodiment of the presentinvention;

FIG. 2 is an exemplary interpolated pixel to be added to the image dataillustrated in FIG. 1 according to an exemplary embodiment of thepresent invention;

FIG. 3 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a first or second method accordingto an exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a third method according to anexemplary embodiment of the present invention;

FIG. 5 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a fourth method according to anexemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a fifth method according to anexemplary embodiment of the present invention;

FIG. 7 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a sixth method according to anexemplary embodiment of the present invention;

FIG. 8A is an exemplary original image input to the display apparatus ofFIG. 1;

FIG. 8B is an exemplary image generated by interpolating the originalimage of FIG. 8A using the linear method;

FIG. 8C is an exemplary image generated by interpolating the originalimage of FIG. 8A using the first method according to an exemplaryembodiment of the present invention;

FIG. 8D is an exemplary image generated by interpolating the originalimage of FIG. 8A using the second method according to an exemplaryembodiment of the present invention;

FIG. 8E is an exemplary image generated by interpolating the originalimage of FIG. 8A using the third method according to an exemplaryembodiment of the present invention;

FIG. 8F is an exemplary image generated by interpolating the originalimage of FIG. 8A using the fourth method according to an exemplaryembodiment of the present invention;

FIG. 8G is an exemplary image generated by interpolating the originalimage of FIG. 8A using the fourth method according to an exemplaryembodiment of the present invention;

FIG. 8H is an exemplary image generated by interpolating the originalimage of FIG. 8A using the fifth method according to an exemplaryembodiment of the present invention;

FIG. 8I is an exemplary image generated by interpolating the originalimage of FIG. 8A using the sixth method according to an exemplaryembodiment of the present invention;

FIG. 8J is an exemplary image generated by interpolating the originalimage of FIG. 8A using the sixth method according to an exemplaryembodiment of the present invention;

FIG. 9A is an exemplary interpolated pixel to be added to image dataaccording to an exemplary embodiment of the present invention;

FIG. 9B is an illustration showing the influence of a nearest referencepixel on a pixel value of the interpolated pixel, shown in FIG. 9A, whenthe pixel value is determined using the linear method;

FIG. 9C is an illustration showing an influence of a nearest referencepixel on a pixel value of the interpolated pixel, shown in FIG. 9A, whenthe pixel value is determined using the second method according to anexemplary embodiment of the present invention;

FIG. 9D is an illustration showing an influence of a nearest referencepixel on a pixel value of the interpolated pixel shown in FIG. 9A, whenthe pixel value is determined using the fourth method according to anexemplary embodiment of the present invention;

FIG. 9E is an illustration showing an influence of a nearest referencepixel on a pixel value of the interpolated pixel shown in FIG. 9A, whenthe pixel value is determined using the sixth method according to anexemplary embodiment of the present invention;

FIG. 10A is an exemplary image generated by interpolating an originalimage using the second method according to an exemplary embodiment ofthe present invention;

FIG. 10B is an exemplary image generated by interpolating an originalimage using the linear method;

FIG. 11 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a, seventh or eighth methodaccording to an exemplary embodiment of the present invention;

FIG. 12 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a ninth method according to anexemplary embodiment of the present invention;

FIG. 13 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a tenth method according to anexemplary embodiment of the present invention;

FIG. 14A is an exemplary original image input to the display apparatusof FIG. 1;

FIG. 14B is an exemplary image generated by interpolating the originalimage of FIG. 14A using the linear method;

FIG. 14C is an exemplary image generated by interpolating the originalimage of FIG. 14A using the cubic convolution method;

FIG. 14D is an exemplary image generated by interpolating the originalimage of FIG. 14A using the seventh method according to an exemplaryembodiment of the present invention;

FIG. 14E is an exemplary image generated by interpolating the originalimage of FIG. 14A using the eighth method according to an exemplaryembodiment of the present invention;

FIG. 14F is an exemplary image generated by interpolating the originalimage of FIG. 14A using the ninth method according to an exemplaryembodiment of the present invention;

FIG. 14G is an exemplary image generated by interpolating the originalimage of FIG. 14A using the tenth method according to an exemplaryembodiment of the present invention;

FIG. 15 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using an eleventh, twelfth, or thirteenthmethod according to an exemplary embodiment of the present invention;

FIG. 16A is an exemplary original image input to the display apparatusof FIG. 1;

FIG. 16B is an exemplary image generated by interpolating the originalimage of FIG. 16A using any one of the first to tenth methods accordingto an exemplary embodiment of the present invention;

FIG. 16C is an exemplary image generated by interpolating the originalimage of FIG. 16A using the eleventh method according to an exemplaryembodiment of the present invention;

FIG. 16D is an exemplary image generated by interpolating the originalimage of FIG. 16A using the twelfth method according to an exemplaryembodiment of the present invention;

FIG. 16E is an exemplary image generated by interpolating the originalimage of FIG. 16A using the thirteenth method according to an exemplaryembodiment of the present invention;

FIG. 16F is an exemplary image generated by interpolating the originalimage of FIG. 16A using the linear method;

FIG. 16G is an exemplary image generated by interpolating the originalimage of FIG. 16A using the cubic convolution method;

FIG. 16H is an exemplary image generated by interpolating the originalimage of FIG. 16A using the method disclosed in the '900 patent;

FIG. 17 is a schematic block diagram illustrating a structure of animage display apparatus according to an exemplary embodiment of thepresent invention;

FIG. 18 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using the fourteenth or fifteenth methodaccording to an exemplary embodiment of the present invention;

FIG. 19 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a sixteenth method according to anexemplary embodiment of the present invention;

FIG. 20 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a seventeenth method according toan exemplary embodiment of the present invention;

FIG. 21 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using an eighteenth method according toan exemplary embodiment of the present invention;

FIG. 22 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a nineteenth method according to anexemplary embodiment of the present invention;

FIG. 23 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twentieth method according to anexemplary embodiment of the present invention;

FIG. 24 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twenty-first method according toan exemplary embodiment of the present invention;

FIG. 25A is an exemplary original image to be input to the displayapparatus of FIG. 1 according to an exemplary embodiment of the presentinvention;

FIG. 25B is an exemplary image generated by interpolating the originalimage of FIG. 25A using the linear method;

FIG. 25C is an exemplary image generated by interpolating the originalimage of FIG. 25A using the twelfth method according to an exemplaryembodiment of the present invention;

FIG. 25D is an exemplary image generated by interpolating the originalimage of FIG. 25A using the sixteenth method according to an exemplaryembodiment of the present invention;

FIG. 25E is an exemplary image generated by interpolating the originalimage of FIG. 25A using the seventeenth method according to an exemplaryembodiment of the present invention;

FIG. 25F is an exemplary image generated by interpolating the originalimage of FIG. 25A using the eighteenth method according to an exemplaryembodiment of the present invention;

FIG. 25G is an exemplary image generated by interpolating the originalimage of FIG. 25A using the second method according to an exemplaryembodiment of the present invention;

FIG. 25H is an exemplary image generated by interpolating the originalimage of FIG. 25A using the nineteenth method according to an exemplaryembodiment of the present invention;

FIG. 25I is an exemplary image generated by interpolating the originalimage of FIG. 25A using the twentieth method according to an exemplaryembodiment of the present invention;

FIG. 25J is an exemplary image generated by interpolating the originalimage of FIG. 25A using the twenty-first method according to anexemplary embodiment of the present invention;

FIG. 25K is an exemplary image generated by interpolating the originalimage of FIG. 25A using the method disclosed in the '900 patent;

FIG. 25L is an exemplary image generated by interpolating the originalimage of FIG. 25A using the cubic convolution method;

FIG. 26 is an illustration of a direct distance of a reference pixelfrom the interpolated pixel of FIG. 2 according to an exemplaryembodiment of the present invention;

FIG. 27 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twenty-second method according toan exemplary embodiment of the present invention;

FIG. 28 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twenty-third method according toan exemplary embodiment of the present invention;

FIG. 29 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twenty-fourth method according toan exemplary embodiment of the present invention;

FIG. 30 is a flowchart illustrating an operation for determining a pixelvalue of an interpolated pixel using a twenty-fifth method according toan exemplary embodiment of the present invention; and

FIG. 31A is an exemplary image generated by interpolating the originalimage of FIG. 25A using the nearest neighbor method;

FIG. 31B is an exemplary image generated by interpolating the originalimage of FIG. 25A using the second method of the present invention;

FIG. 31C is an exemplary image generated by interpolating the originalimage of FIG. 25A using the twenty-second method according to anexemplary embodiment of the present invention;

FIG. 31D is an exemplary image generated by interpolating the originalimage of FIG. 25A using the twenty-third method according to anexemplary embodiment of the present invention;

FIG. 32A is an exemplary original image having gradation;

FIG. 32B is an exemplary image generated by interpolating the originalimage of FIG. 32A using the twenty-second method according to anexemplary embodiment of the present invention; and

FIG. 32C is an exemplary image generated by interpolating the originalimage of FIG. 32A using the twenty-third method according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In describing the preferred embodiments illustrated in the drawings,specific terminology is employed for clarity. However, the disclosure ofthis patent specification is not intended to be limited to the specificterminology selected and it is to be understood that each specificelement includes all technical equivalents that operate in a similarmanner. Referring now to the drawings, wherein like reference numeralsdesignate identical or corresponding parts throughout the several views,FIG. 1 illustrates an image display apparatus 10 according to anexemplary embodiment of the present invention.

The image display apparatus 10 includes any kind of display apparatuscapable of displaying an image according to image data 1, such as a CRT(cathode ray tube) display, LCD (liquid crystal display), PDP (plasmadisplay panel), or a projector, for example.

As shown in FIG. 1, the image display apparatus 10 includes an imageprocessing device 9 and a display device 8. Once the image data 1 isinput into the image display apparatus 10, the image processing device 9detects the resolution (“input resolution”) of the image data 1, andcompares it with the resolution (“output resolution”) of the displaydevice 8. Based on the comparison, the image processing device 9converts the image data 1 from the input resolution to the outputresolution. The converted image data 1 is then output to the displaydevice 8 to be displayed on the display device 8.

As shown in FIG. 1, the image processing device 9 includes input datastorage 4, resolution detector 2, coordinate selector 3, resolutionconverter 5, conversion data storage 6, and output data storage 7.

The input data storage 4, which may be optionally provided, stores theimage data 1, preferably, in a unit basis. For example, the image data 1may be stored in a pixel basis, line basis, or frame basis.

The resolution detector 2 detects the input resolution of the image data1 using a clock signal, a horizontal synchronization signal, or avertical synchronization signal, for example.

The coordinate selector 3 selects a coordinate for the input resolution(“input coordinate”), and a coordinate for the output resolution(“output coordinate”), respectively. In one example, the coordinateselector 3 may store a plurality of look-up tables (LUTs), eachcorresponding to a specific resolution. In another example, thecoordinate selector 3 may generate a LUT based on the input or outputresolution.

The resolution converter 5 converts the image data 1 from the inputresolution to the output resolution by changing the density of pixels inthe image data 1.

In one example, if the output resolution is lower than the inputresolution, the resolution converter 5 may delete a number of pixels(“deleted pixels”) throughout the image data 1. The resolution converter5 selects the deleted pixels from the image data 1 based on the inputand output coordinates.

In another example, if the output resolution is higher than the inputresolution, the resolution converter 5 may add a number of pixels(“interpolated pixels”) throughout the image data 1. The resolutionconverter 5 determines a portion, in the image data 1, to which each ofthe interpolated pixels is added based on the input and outputcoordinates. Further, the resolution converter 5 determines a pixelvalue of each of the interpolated pixels based on information containedin the image data 1 using various interpolation methods as describedbelow.

The conversion data storage 6 stores various data including data usedfor resolution conversion.

The output data storage 7, which may be optionally provided, stores theprocessed image data 1 having the output resolution, and outputs theprocessed image data 1, preferably, in a unit basis.

Referring now to FIGS. 2 and 3, operations for determining a pixel valueof an interpolated pixel using first and second methods are explained,respectively, according to an exemplary embodiment of the presentinvention.

According to the first method, Step S100 specifies one of theinterpolated pixels. For example, as shown in FIG. 2, the resolutionconverter 5 may specify an interpolated pixel B.

Step S101 selects one or more reference pixels, which are originallyprovided in the image data 1, from a vicinity of the specifiedinterpolated pixel. Step S101 further obtains a distance value for eachof the reference pixels.

To select the reference pixels, the resolution converter 5 maycalculate, for each of the interpolated pixels, a distance between theinterpolated pixel and its neighboring pixel based on the input andoutput coordinates. The distance may be expressed in X and Y coordinatevalues. For example, if the interpolated pixel is positioned at thecoordinate (X1, Y1), and its neighboring pixel is positioned at thecoordinate (X2, Y2), the distance between the interpolated pixel and theneighboring pixel may be expressed in X and Y coordinate values (X1-X2)and (Y1-Y2). The calculated distance values are further stored in theconversion data storage 6 as a LUT. Using this LUT, the resolutionconverter 5 can select one or more reference pixels for each of theinterpolated pixels in the image data 1. Further, the resolutionconverter 5 can obtain a distance value for each of the selectedreference pixels from the LUT.

In the example shown in FIG. 2, the resolution converter 5 selects thefirst to fourth reference pixels A00, A01, A10, and A11, from a vicinityof the interpolated pixel B. For each of the reference pixels A00 toA11, the resolution converter 5 obtains a distance value expressed in Xand Y coordinate values. In this exemplary embodiment, the firstreference pixel A00 has a distance value (x1, y1). The second referencepixel A01 has a distance value (x1, y2). The third reference pixel A10has a distance value (x2, y1). The fourth reference pixel A11 has adistance value (x2, y2). In the example shown in FIG. 2, four referencepixels are selected, however, the resolution converter 5 may select anynumber of reference pixels.

Step S102 obtains a pixel value for each of the reference pixelsobtained in Step S101, for example, from the input data storage 4. Inthe example shown in FIG. 2, the first reference pixel A00 has a pixelvalue a00. The second reference pixel A01 has a pixel value a01. Thethird reference pixel A10 has a pixel value a10. The fourth referencepixel A11 has a pixel value a11.

Step S103 obtains a difference value M, indicating a difference betweena maximum value MAX and a minimum value MIN of the reference pixels. Themaximum value MAX corresponds to the pixel value having the largestvalue selected from the pixel values of the reference pixels. Theminimum value MIN corresponds to the pixel having the smallest valueselected from the pixel values of the reference pixels. The differencevalue M may be expressed with the equation: M=MAX−MIN.

Alternatively, the difference value M may be obtained by comparing thepixel value of a nearest reference pixel with the pixel value of each ofthe reference pixels other than the nearest reference pixel. The nearestreference pixel is a reference pixel having the smallest distance value.For example, in the example shown in FIG. 2, if the fourth referencepixel corresponds to the nearest reference pixel, the difference betweenthe pixel value a11 and the pixel value a10 (|a11−a10|), the differencebetween the pixel value a11 and the pixel value a10 (|a11−a10|), and thedifference between the pixel value a11 and the pixel value a00(|a11−a00|) may be obtained, respectively. The maximum value of theobtained differences is used as the difference value M.

Step S104 determines whether the difference value M is equal to 0. Ifthe difference value M is equal to 0 (“YES” in Step S104), that is, thepixel values are the same for all the reference pixels, the operationproceeds to Step S108. If the difference value M is not equal to 0 (“NO”in Step S104), the operation proceeds to Step S105.

Step S108 uses one of the pixel values of the reference pixels as apixel value of the interpolated pixel. In the example shown in FIG. 2,the pixel value a00 may be used as a pixel value b of the interpolatedpixel B. However, any one of the pixel values a00, a01, a10, and a11 maybe used, as they have the same values.

Step S105 calculates an average value AVE, which is the average of thepixel values of the reference pixels. In the example shown in FIG. 2,the average value AVE of the reference pixels A00, A10, A01, and A11 canbe calculated with the equation: AVE=(a00+a01+a10+a11)/4.

Step S106 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, the average value AVE obtained in Step S105, anda normalization factor. In this exemplary embodiment, a maximum pixelvalue of the image data 1, which is 255, is used as the normalizationfactor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/255);Z 10=x 1*y 2*(1−|a 10−AVE|/255);Z 01=x 2*y 1*(1−|a 01−AVE|/255); andZ 11=x 1*y 1*(1−|a 11−AVE|/255).

Step S107 calculates a pixel value of the interpolated pixel using thepixel values of the reference pixels. In this exemplary embodiment, eachof the pixel values is weighted with the corresponding weighting factorobtained in Step S106.

In the example shown in FIG. 2, the pixel values a00, a10, a01, and a11are weighted with the weighting factors Z00, Z10, Z01 and Z11,respectively. Thus, the pixel value b of the interpolated pixel B may beobtained as follows:b=a 00*Z 00/(Z 00+Z 10+Z 01+Z 11)+a 10*Z 10/(Z 00+Z 10+Z 01+Z 11)+a 01*Z01/(Z 00+Z 10+Z 01+Z 11)+a 11*Z 11/(Z 00+Z 10+Z 01+Z 11).

The above equation can be simplified as:b=(Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11)/(Z 00+Z 10+Z 01+Z 11).

Step S109 determines whether all interpolated pixels in the image data 1have been processed. If all interpolated pixels have been processed(“YES” in Step S109), the operation ends to store the processed imagedata 1 in the output data storage 7 to be displayed by the displaydevice 10. If all interpolated pixels have not been processed (“NO” inStep S109), the operation returns to Step S100 to specify anotherinterpolated pixel.

Using the first method, smoothness of an image may be increased as shownin FIG. 8C when compared to the image of FIG. 8B, which is generatedusing the linear method.

The operation using the second method is substantially similar to theoperation using the first method, except for the calculation performedin Step S106.

According to the second method, Step S106 obtains a weighting factor foreach of the reference pixels using the pixel values obtained in StepS102, the distance values obtained in Step S101, the average value AVEobtained in Step S105, and a normalization factor. In this exemplaryembodiment, the difference value M obtained in Step S103 is used as thenormalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/M);Z 10=x 1*y 2*(1−|a 10−AVE|/M);Z 01=x 2*y 1*(1−|a 01−AVE|/M); andZ 11=x 1*y 1*(1−|a 11−AVE|/M).

Using the second method, smoothness of an image may be increased asshown in FIG. 8D when compared to the image of FIG. 8B, which isgenerated using the linear method. Further, an image generated using thesecond method tends to keep more information regarding pixel values ofan original image as illustrated in FIG. 9C when compared to the linearmethod. Referring to the image of FIG. 9B, which is generated using thelinear method, the pixel value of an interpolated pixel B is influencedby the pixel value of the nearest reference pixel (indicated with awhite pixel in FIG. 9A). However, referring to the image of FIG. 9C,which is generated using the second method, the influence of the pixelvalue of the nearest reference pixel is suppressed. Accordingly, thesecond method may be more effective than the linear method forsuppressing jaggedness of a diagonal line, as it can be seen from thecomparison between the image of FIG. 10A generated by using the secondmethod and the image of FIG. 10B generated by using the linear method.

In this exemplary embodiment, the difference value M is used as thenormalization factor. However, any value may be used as long as itreflects the pixel values of the reference pixels. For example, a valuelarger than the value (MAX−AVE), a value larger than the value(AVE−MIN), a value smaller or larger than the difference value M by apredetermined value may be used.

Referring now to FIGS. 2 and 4, an operation for determining a pixelvalue of an interpolated pixel using a third method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the third method shown in FIG. 4 is substantiallysimilar to the operation using the first method shown in FIG. 3. Thedifferences include the deletion of Steps S103, S104, and S108,replacement of Step S105 with Step S205, and replacement of Step S106with Step S206.

Step S205 calculates an average value AVE1, which is the average of thepixel values of a pair of reference pixels that are diagonally oppositeeach other.

In the example shown in FIG. 2, the first reference pixel A00 and thefourth reference pixel A11 make a pair of diagonally opposing pixels.Accordingly, the average value AVE11 of the reference pixels A00 and A11can be calculated as follows: AVE11=(a00+a11)/2.

Similarly, the second reference pixel A01 and the third reference pixelA10 make a pair of diagonally opposing pixels. Accordingly, the averagevalue AVE12 of the reference pixels A01 and A10 can be calculated asfollows: AVE12=(a01+a10)/2.

Step S206 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, the average values AVE1 obtained in Step S205,and a normalization factor. In this exemplary embodiment, apredetermined value larger than the maximum pixel value of the imagedata 1, which is 255, is used as the normalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE12|/256);Z 10=x 1*y 2*(1−|a 10−AVE11|/256);Z 01=x 2*y 1*(1−|a 01−AVE11|/256); andZ 11=x 1*y 1*(1−|a 11−AVE12|/256).

Using the third method, sharpness of an image may be increased as shownin FIG. 8E when compared to the image of FIG. 8B, which is generatedusing the linear method.

Referring now to FIGS. 2 and 5, an operation for determining a pixelvalue of an interpolated pixel using a fourth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the fourth method shown in FIG. 5 is substantiallysimilar to the operation using the third method shown in FIG. 4. Thedifferences include the addition of Step S303, and replacement of StepS206 with Step S306.

Step S303 obtains a difference value M1 based on the maximum value MAXand the minimum value MIN of the reference pixels. The difference valueM1 is any kind of value larger than the difference value M obtained inStep S103 of FIG. 3. For example, the difference value M1 may beexpressed with the equation: M1=MAX−MIN+α, with α being any value largerthan 0. In this exemplary embodiment, α is set to 1.

Step S306 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, the average value AVE1 obtained in Step S205, anda normalization factor. In this exemplary embodiment, the differencevalue M1 obtained in Step S303 is used as the normalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE12|/M 1);Z 10=x 1*y 2*(1−|a 10−AVE11|/M 1);Z 01=x 2*y 1*(1−|a 01−AVE11|/M 1); andZ 11=x 1*y 1*(1−|a 11−AVE12|/M 1).

Using the fourth method, sharpness of an image may be increased as shownin FIG. 8F when compared to the image of FIG. 8B, which is generatedusing the linear method. Further, an image generated using the fourthmethod tends to keep more information regarding pixel values of anoriginal image, as illustrated in FIG. 9D when compared to the linearmethod. Referring to the image of FIG. 9B, which is generated using thelinear method, the interpolated pixel B is influenced by the nearestreference pixel (indicated with a white pixel in FIG. 9A). However,referring to the image of FIG. 9D, which is generated using the fourthmethod, the influence of the nearest reference pixel is suppressed.Accordingly, the fourth method may be more effective than the linearmethod for suppressing the jaggedness of a diagonal line.

In this exemplary embodiment, the difference value M1 is used as thenormalization factor. However, any value may be used as long as itreflects the pixel values of the reference pixels. For example, thevalue of the normalization factor may be increased to improve smoothnessof an image, as illustrated in FIG. 8G. The image shown in FIG. 8G,which is generated using the normalization factor of (M1*1.3), tends tobe smoother than the image shown in FIG. 8F, which is generated usingthe normalization factor of M1.

Referring now to FIGS. 2 and 6, an operation for determining a pixelvalue of an interpolated pixel using a fifth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the fifth method shown in FIG. 6 is substantiallysimilar to the operation using the third method shown in FIG. 4. Thedifferences include the deletion of Steps S205 and S303, and replacementof Step S206 with Step S406.

Step S406 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, and a normalization factor. In this exemplaryembodiment, a predetermined value larger than the maximum pixel value ofthe image data 1, which is 255, is used as the normalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−a 11|/256);Z 10=x 1*y 2*(1−|a 10−a 01|/256);Z 01=x 2*y 1*(1−|a 01−a 10|/256); andZ 11=x 1*y 1*(1−|a 11−a 00|/256).

As shown in the above equations, instead of using the average value AVE1as described with reference to Step S206 of FIG. 4, the third methodcalculates a weighting factor of a target reference pixel using thepixel value of a reference pixel diagonally opposite to the targetreference pixel.

Using the fifth method, sharpness of an image may be increased as shownin FIG. 8H when compared to the image of FIG. 8B, which is generatedusing the linear method.

Referring now to FIGS. 2 and 7, an operation for determining a pixelvalue of an interpolated pixel using a sixth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the sixth method shown in FIG. 7 is substantiallysimilar to the operation using the fourth method shown in FIG. 5. Thedifferences include the deletion of Step S205, and replacement of StepS306 with Step S506.

Step S506 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, and a normalization factor. In this exemplaryembodiment, the difference value M1 obtained in Step S303 is used as thenormalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−a 11|/M 1);Z 10=x 1*y 2*(1−|a 10−a 01|/M 1);Z 01=x 2*y 1*(1−|a 01−a 10|/M 1); andZ 11=x 1*y 1*(1−|a 11−a 00|/M 1).

As shown in the above equations, instead of using the average value AVE1as described referring to Step S306 of FIG. 5, the third examplecalculates a weighting factor for a target reference pixel using thepixel value of a reference pixel diagonally opposite the targetreference pixel.

Using the sixth method, sharpness of an image may be increased as shownin FIG. 8I when compared to the image of FIG. 8B, which is generatedusing the linear method. Further, an image generated using the sixthmethod tends to keep more information regarding pixel values of anoriginal image, as illustrated in FIG. 9E when compared to the linearmethod. Referring to the image of FIG. 9B, which is generated using thelinear method, the interpolated pixel B is influenced by the nearestreference pixel (indicated with a white pixel in FIG. 9A). However,referring to the image of FIG. 9E, which is generated using the sixthmethod, the influence of the nearest reference pixel is suppressed.Accordingly, the sixth method may be more effective than the linearmethod for suppressing the jaggedness of a diagonal line.

In this exemplary embodiment, the difference value M1 is used as thenormalization factor. However, any value may be used as long as itreflects the pixel values of the reference pixels. For example, thevalue of the normalization factor may be increased to improve smoothnessof an image, as illustrated in FIG. 8J. The image shown in FIG. 8J,which is generated using the normalization factor of (M1*1.3), tends tobe smoother than the image shown in FIG. 8I, which is generated usingthe normalization factor of M1.

Referring now to FIGS. 2 and 11, operations for determining a pixelvalue of an interpolated pixel using seventh and eighth methods areexplained, respectively, according to an exemplary embodiment of thepresent invention.

The operation using the seventh method shown in FIG. 11 is substantiallysimilar to the operation using the first method shown in FIG. 3. Thedifferences include the addition of Step S605, and replacement of StepS106 with Step S606.

Step S605 selects a nearest reference pixel A, which is the referencepixel having the smallest distance value, from the reference pixelsobtained in Step S101. In this exemplary embodiment, a distance valuemay be expressed in X and Y coordinate values.

According to the seventh method, Step S606 obtains a weighting factorfor each of the reference pixels, other than the nearest reference pixelA using the pixel values obtained in Step S102, the distance valuesobtained in Step S101, the average value AVE obtained in Step S105, anda normalization factor, in a substantially similar manner as describedwith reference to Step S106 of FIG. 3. In this exemplary embodiment, themaximum pixel value of the image data 1, which is 255, is used as thenormalization factor. Further, Step S606 obtains a weighting factor forthe nearest reference pixel A using the distance value of the nearestreference pixel A obtained in Step S101.

In the example shown in FIG. 2, if the reference pixel A00 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2;Z 10=x 1*y 2*(1−|a 10−AVE|/255);Z 01=x 2*y 1*(1−|a 01−AVE|/255); andZ 11=x 1*y 1*(1−|a 11−AVE|/255).

In the example shown in FIG. 2, if the reference pixel A10 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/255);Z 10=x 1*y 2;Z 01=x 2*y 1*(1−|a 01−AVE|/255); andZ 11=x 1*y 1*(1−|a 11−AVE|/255).

In the example shown in FIG. 2, if the reference pixel A01 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/255);Z 10=x 1*y 2*(1−|a 10−AVE|/255);Z 01=x 2*y 1; andZ 11=x 1*y 1*(1−|a 11−AVE|/255).

In the example shown in FIG. 2, if the reference pixel A11 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/255);Z 10=x 1*y 2*(1−|a 10−AVE|/255);Z 01=x 2*y 1*(1−|a 01−AVE|/255); andZ 11=x 1*y 1.

Using the seventh method, sharpness of an image may be increased asshown in FIG. 14D when compared to the image of FIG. 14B, which isgenerated using the linear method. Further, the seventh method may bemore effective than the cubic convolution method for suppressing a noisecomponent of an original image. The image of FIG. 14C, which isgenerated using the cubic convolution method, keeps more informationregarding pixel values of an original image as compared to the linearmethod. However, the image of FIG. 14C may contain information that isunnecessary for determining a pixel value of an interpolated pixel, thuscausing some noises in the image.

The operation using the eighth method is substantially similar to theoperation using the seventh method, except for the calculation performedin Step S606.

According to the eighth method, Step S606 obtains a weighting factor foreach of the reference pixels other than the nearest reference pixel Ausing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, the average value AVE obtained in Step S105, anda normalization factor, in a substantially similar manner as describedwith reference to Step S106 of FIG. 3. In this exemplary embodiment, thedifference value M obtained in Step S103 is used as the normalizationfactor. Further, Step S606 obtains a weighting factor for the nearestreference pixel A using the distance value of the nearest referencepixel A obtained in Step S101.

In the example shown in FIG. 2, if the reference pixel A00 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2;Z 10=x 1*y 2*(1−|a 10−AVE|/M);Z 01=x 2*y 1*(1−|a 01−AVE|/M); andZ 11=x 1*y 1*(1−|a 11−AVE|/M).

In the example shown in FIG. 2, if the reference pixel A10 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/M);Z 10=x 1*y 2;Z 01=x 2*y 1*(1−|a 01−AVE|/M); andZ 11=x 1*y 1*(1−|a 11−AVE|/M).

In the example shown in FIG. 2, if the reference pixel A01 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/M);Z 10=x 1*y 2*(1−|a 10−AVE|/M);Z 01=x 2*y 1; andZ 11=x 1*y 1*(1−|a 11−AVE|/M).

In the example shown in FIG. 2, if the reference pixel A11 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/M);Z 10=x 1*y 2*(1−|a 10−AVE|/M);Z 01=x 2*y 1*(1−|a 01−AVE|/M); andZ 11=x 1*y 1.

Using the eighth method, sharpness of an image may be increased whilekeeping information regarding pixel values of an original image as shownin FIG. 14E when compared to the image of FIG. 14B, which is generatedusing the linear method. Further, the eighth method may be moreeffective than the cubic convolution method for suppressing a noisecomponent of an original image, as illustrated in FIGS. 14C and 14E.

In this exemplary embodiment, the difference value M is used as thenormalization factor. However, any value may be used as long as itreflects the pixel values of the reference pixels. For example, a valuelarger than the value (MAX−AVE), a value larger than the value(AVE−MIN), or a value smaller or larger than the difference value M maybe used.

Referring now to FIGS. 2 and 12, an operation for determining a pixelvalue of an interpolated pixel using a ninth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the ninth method shown in FIG. 12 is substantiallysimilar to the operation using the third method shown in FIG. 4. Thedifferences include the addition of Step S605, and replacement of StepS206 with Step S706.

Step S706 obtains a weighting factor for each of the reference pixelsother than the nearest reference pixel A using the pixel values obtainedin Step S102, the distance values obtained in Step S101, the averagevalues AVE1 obtained in Step S205, and a normalization factor, in asubstantially similar manner as described referring to Step S206 of FIG.4. In this exemplary embodiment, a predetermined value larger than themaximum pixel value of the image data 1, which is 255, is used as thenormalization factor. Further, Step S706 obtains a weighting factor forthe nearest reference pixel A using the distance value of the nearestreference pixel A obtained in Step S101.

In the example shown in FIG. 2, if the reference pixel A00 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2;Z 10=x 1*y 2*(1−|a 10−AVE11|/256);Z 01=x 2*y 1*(1−|a 01−AVE11|/256); andZ 11=x 1*y 1*(1−|a 11−AVE12|/256).

In the example shown in FIG. 2, if the reference pixel A10 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE12|/256);Z 10=x 1*y 2;Z 01=x 2*y 1*(1−|a 01−AVE11|/256); andZ 11=x 1*y 1*(1−|a 11−AVE12|/256).

In the example shown in FIG. 2, if the reference pixel A01 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE12|/256);Z 10=x 1*y 2*(1−|a 10−AVE11|/256);Z 01=x 2*y 1; andZ 11=x 1*y 1*(1−|a 11−AVE12|/256).

In the example shown in FIG. 2, if the reference pixel A11 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE12|/256);Z 10=x 1*y 2*(1−|a 10−AVE11|/256);Z 01=x 2*y 1*(1−|a 01−AVE11|/256); andZ 11=x 1*y 1.

Using the ninth method, sharpness of an image may be increased as shownin FIG. 14F when compared to the image of FIG. 14B, which is generatedusing the linear method. Further, the ninth method may be more effectivethan the cubic convolution method for suppressing a noise component ofan original image, as illustrated in FIGS. 14C and 14F.

Referring now to FIGS. 2 and 13, an operation for determining a pixelvalue of an interpolated pixel using a tenth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the tenth method shown in FIG. 13 is substantiallysimilar to the operation using the fifth method shown in FIG. 6. Thedifferences include the addition of Step S605, and replacement of StepS406 with Step S806.

According to the tenth method, Step S806 obtains a weighting factor foreach of the reference pixels other than the nearest reference pixel Ausing the pixel values obtained in Step S102, the distance valuesobtained in Step S101, and a normalization factor, in a substantiallysimilar manner as described referring to Step S406 of FIG. 6. In thisexemplary embodiment, a predetermined value larger than the maximumpixel value of the image data 1, which is 255, is used as thenormalization factor. Further, Step S806 obtains a weighting factor forthe nearest reference pixel A using the distance value of the nearestreference pixel A obtained in Step S101.

In the example shown in FIG. 2, if the reference pixel A00 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2;Z 10=x 1*y 2*(1−|a 10−a 01|/256);Z 01=x 2*y 1*(1−|a 01−a 10|/256); andZ 11=x 1*y 1*(1−|a 11−a 00|/256).

In the example shown in FIG. 2, if the reference pixel A10 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−a 11|/256);Z 10=x 1*y 2;Z 01=x 2*y 1*(1−|a 01−a 10|/256); andZ 11=x 1*y 1*(1−|a 11−a 00|/256).

In the example shown in FIG. 2, if the reference pixel A01 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−a 11|/256);Z 10=x 1*y 2*(1−|a 10−a 01|/256);Z 01=x 2*y 1; andZ 11=x 1*y 1*(1−|a 11−a 00|/256).

In the example shown in FIG. 2, if the reference pixel A11 correspondsto the nearest reference pixel A, weighting factors Z00, Z10, Z01, andZ11 for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=x 2*y 2*(1−|a 00−a 11|/256);Z 10=x 1*y 2*(1−|a 10−a 01|/256);Z 01=x 2*y 1*(1−|a 01−a 10|/256); andZ 11=x 1*y 1.

Using the tenth method, sharpness of an image may be increased as shownin FIG. 14G when compared to the image of FIG. 14B, which is generatedusing the linear method. Further, the tenth method may be more effectivethan the cubic convolution method for suppressing a noise component ofan original image, as illustrated in FIGS. 14C and 14G.

Referring now to FIGS. 2 and 15, operations for determining a pixelvalue of an interpolated pixel using eleventh, twelfth and thirteenthmethods are explained, respectively, according to an exemplaryembodiment of the present invention.

The operation using any one of the eleventh to thirteenth methods shownin FIG. 15 is substantially similar to the operation using the secondmethod shown in FIG. 3. The differences include the replacement of StepS106 with Step S906.

According to the eleventh method, Step S906 obtains a weighting factorfor each of the reference pixels using the pixel values obtained in StepS102, the distance values obtained in Step S101, the average value AVEobtained in Step S105, and a normalization factor. In this exemplaryembodiment, the difference value M obtained in Step S103 is used as thenormalization factor. Further, in this exemplary embodiment, thedistance value is raised to the power of a multiplication value n. Themultiplication value n is an arbitrary number larger than 1, preferablylarger than 2.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=(x 2*y 2)^(n)*(1−|a 00−AVE|/M);Z 10=(x 1*y 2)^(n)*(1−|a 10−AVE|/M);Z 01=(x 2*y 1)^(n)*(1−|a 01−AVE|/M); andZ 11=(x 1*y 1)^(n)*(1−|a 11−AVE|/M).

Using the eleventh method, sharpness of an image may be increased asshown in FIG. 16C,when compared to the image of FIG. 16B, which isgenerated using one of the first to tenth methods of the presentinvention. Further, the eleventh method may be more effective than theknown methods for improving sharpness and smoothness of an originalimage. The known methods includes, for example, the linear method (FIG.16F), the cubic convolution method (FIG. 16G), or the method disclosedin the '900 patent (FIG. 16H).

The operation using the twelfth method is substantially similar to theoperation using the eleventh method, except for the calculationperformed in Step S906.

According to the twelfth method, Step S906 obtains a weighting factorfor each of the reference pixels using the pixel values obtained in StepS102, the distance values obtained in Step S101, the average value AVEobtained in Step S105, and a normalization factor. In this exemplaryembodiment, the difference value M obtained in Step S103 is used as thenormalization factor. Further, in this exemplary embodiment, the pixelvalue is raise to the power of a multiplication value n. Themultiplication value n is an arbitrary number larger than 1, preferablylarger than 2.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=(x 2*y 2)*(1−|a 00−AVE|/M)^(n);Z 10=(x 1*y 2)*(1−|a 10−AVE|/M)^(n);Z 01=(x 2*y 1)*(1−|a 01−AVE|/M)^(n); andZ 11=(x 1*y 1)*(1−|a 11−AVE|/M)^(n).

Using the twelfth method, sharpness of an image may be increased whilekeeping smoothness of the image, as shown in FIG. 16D, when compared tothe image of FIG. 16B, which is generated using one of the first totenth methods of the present invention. Further, the twelfth method maybe more effective than the known methods for improving sharpness andsmoothness of an original image. The known methods includes, forexample, the linear method (FIG. 16F), the cubic convolution method(FIG. 16G), or the method disclosed in the '900 patent (FIG. 16H).

The operation using the thirteenth method is substantially similar tothe operation using the eleventh method, except for the calculationperformed in Step S906.

According to the thirteenth method, Step S906 obtains a weighting factorfor each of the reference pixels using the pixel values obtained in StepS102, the distance values obtained in Step S101, the average value AVEobtained in Step S105, and a normalization factor. In this exemplaryembodiment, the difference value M obtained in Step S103 is used as thenormalization factor. Further, in this exemplary embodiment, thedistance value and the pixel values are raised to the power ofmultiplication values n and p, respectively. Any one of themultiplication values n and the value p is an arbitrary number largerthan 1, preferably, larger than 2.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=(x 2*y 2)^(n)*(1−|a 00−AVE|/M)^(p);Z 10=(x 1*y 2)^(n)*(1−|a 10−AVE|/M)^(p);Z 01=(x 2*y 1)^(n)*(1−|a 01−AVE|/M)^(p); andZ 11=(x 1*y 1)^(n)*(1−|a 11−AVE|/M)^(p).

If the factor n is equal to the factor p, the above equations can besimplified as follows:Z 00=((x 2*y 2)*(1−|a 00−AVE|/M))^(n);Z 10=((x 1*y 2)*(1−|a 10−AVE|/M))^(n);Z 01=((x 2*y 1)*(1−|a 01−AVE|/M))^(n); andZ 11=((x 1*y 1)*(1−|a 11−AVE|/M))^(n).

Using the thirteenth method, sharpness of an image may be increasedwhile keeping smoothness of the image, as shown in FIG. 16E, whencompared to the image of FIG. 16B, which is generated using one of thefirst to tenth methods of the present invention. Further, the thirteenthmethod may be more effective than the known methods for improvingsharpness and smoothness of an original image. The known methodsincludes, for example, the linear method (FIG. 16F), the cubicconvolution method (FIG. 16G), or the method disclosed in the '900patent (FIG. 16H).

In this exemplary embodiment, sharpness and smoothness of an image maybe adjusted, by changing the multiplication value of n or p. Forexample, with the increased value n, a pixel value of an interpolatedpixel may be influenced more by a pixel value of its nearest referencepixel. Accordingly, sharpness of the image may be increased. With theincreased value p, a pixel value of an interpolated pixel may beinfluenced more by an average pixel value of the entire image.Accordingly, smoothness of the image may be increased.

According to any one of the above-described and other methods of thepresent invention, the resolution converter 5 may store calculationresults in the conversion data storage 6. Alternatively, the imageprocessing device 9 of FIG. 1 may be additionally provided with a datastorage capable of storing various data including the calculationresults generated by the resolution converter 5. The additional datastorage may increase the processing speed of the image processing device9, especially when multiplication of the pixel values or the distancevalues are performed as described above with reference to any one of theeleventh to thirteenth methods.

For example, an add value data storage 11 may be additionally providedto the image processing device 9, as shown in FIG. 17. The add valuedata storage 11 stores a plurality of weighting factors beforemultiplication and a plurality of add values in a corresponding manneras a LUT. The resolution converter 5 may multiply the weighting factorsusing the add values obtained from the add value data storage 11.

Referring now to FIGS. 2 and 18, operations for determining a pixelvalue of an interpolated pixel using the fourteenth and fifteenthmethods are explained, respectively, according to an exemplaryembodiment of the present invention.

The operation using the fourteenth method shown in FIG. 18 issubstantially similar to the operation using the first method shown inFIG. 3. The differences include the addition of Steps S1007 and S1008.

According to the fourteenth method, Step S1007 obtains an add value foreach of the weighting factors obtained in Step S106 from the LUT storedin the add value data storage 11.

Step S1008 multiplies the weighting factor by the corresponding addvalue to obtain a multiplied weighting factor.

The operation using the fifteenth method is substantially similar to theoperation using the fourteenth method, except for the calculationperformed in Step S1008.

Step S1008 adds the add value to the weighting factor to obtain amultiplied weighting factor.

Using any one of the fourteenth and fifteenth methods, the processingspeed of the resolution converter 5 may be increased.

In addition to the above-described methods including the first tofifteenth methods, the resolution converter 5 may perform anyinterpolation method according to the scope of this disclosure andappended claims. For example, elements, features, or functions of theabove-described methods may be combined with each other and/orsubstituted for each other within the scope of this disclosure andappended claims. In operation, the resolution converter 5 may select atleast one of the above-described and other methods of the presentinvention according to a user's preference, for example. Alternatively,the resolution converter 5 may select at least one of theabove-described and other methods of the present invention according toentire or local image characteristics. To make a selection, the imageprocessing device 9 may be additionally provided with a selector capableof selecting at least one of the above-described and other methods ofthe present invention according to a user's preference orcharacteristics of an image.

Further, in addition to any one of the above-described and other methodsof the present invention, the resolution converter 5 may perform any oneof the known interpolation methods, including the linear method, cubicconvolution method, or the nearest neighbor method, for example. Inoperation, the resolution converter 5 may select at least one of theabove-described and other methods of the present invention, and theknown interpolation methods according to a user's preference.Alternatively, the resolution converter 5 may select at least one of theabove-described and other methods of the present invention, and theknown interpolation methods according to entire or local imagecharacteristics. To make a selection, the image processing device 9 maybe additionally provided with a selector capable of selecting at leastone of the above-described and other methods of the present invention,and the known interpolation methods according to a user's preference orcharacteristics of an image.

Referring now to FIGS. 2 and 19, an operation for determining a pixelvalue of an interpolated pixel using a sixteenth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the sixteenth method shown in FIG. 19 issubstantially similar to the operation using the first method shown inFIG. 3. The differences include the addition of Steps S1105 and S1107,and replacement of Step S106 with S906.

Step S1105 determines whether the difference value M obtained in StepS103 is equal to or larger than a predetermined selection value. If thedifference value M is smaller than the selection value (“NO” in StepS1105), the operation proceeds to Step S1107. If the difference value Mis equal to or larger than the selection value (“YES” in Step S1105),the operation proceeds to Step S105.

As described with reference to FIG. 3, the difference value M indicatesa difference between a maximum value MAX and a minimum value MIN of thereference pixels. In this exemplary embodiment, the selection valuecorresponds to any pixel value between 0 and 255, which may be used forselecting an interpolation method suitable for processing the specifiedinterpolated pixel. For example, the selection value may be set to thepixel value of 128. Further, in this exemplary embodiment, theresolution converter 5 is assumed to select either one of theinterpolation methods including the twelfth method of the presentinvention and the linear method. However, the resolution converter 5 iscapable of selecting at least one of the interpolation methods,including any one of the methods of the present invention and the knownmethods.

As described above, if the difference value M of the reference pixels issmaller than the selection value, the resolution converter 5 assumesthat variations in pixel values of the reference pixels are relativelysmall. Based on this characteristic, the linear method is selected,which is suitable for enhancing smoothness of the image. Examples of animage having small variations in pixel values include an image having acharacter or a line.

If the difference value M of the reference pixels is equal to or largerthan the selection value, the resolution converter 5 assumes thatvariations in pixel values of the reference pixels are relatively large.Based on this characteristic, the twelfth method is selected, which issuitable for enhancing sharpness of the image. Examples of an imagehaving large variations in pixel values include an image having apicture image.

Step S1107 obtains a weighting factor for each of the reference pixelsusing the linear method. In the example shown in FIG. 2, weightingfactors Z00, Z10, Z01, and Z11 for the reference pixels A00, A10, A01,and A11 are obtained, respectively, as follows:Z 00=x 2*y 2;Z 10=x 1*y 2;Z 01=x 2*y 1; andZ 11=x 1*y 1.

Step S906 obtains a weighting factor for each of the reference pixelsusing the twelfth method of the present invention. In the example shownin FIG. 2, weighting factors Z00, Z10, Z01, and Z11 for the referencepixels A00, A10, A01, and A11 are obtained, respectively, as follows:Z 00=(x 2*y 2)*(1−|a 00−AVE|/M)^(n);Z 10=(x 1*y 2)*(1−|a 10−AVE|/M)^(n);Z 01=(x 2*y 1)*(1−|a 01−AVE|/M)^(n); andZ 11=(x 1*y 1)*(1−|a 11−AVE|/M)^(n).

In this exemplary embodiment, the multiplication value n is set to 3,however, any number larger than 1, preferably larger than 2, may beused.

Step S107 calculates a pixel value of the interpolated pixel using thepixel values of the reference pixels. In this exemplary embodiment, eachof the pixel values is weighted with the corresponding weighting factorobtained in Step S906 or S1107.

In the example shown in FIG. 2, if the linear method is selected, thepixel values a00, a10, a01, and a11 are weighted with the weightingfactors Z00, Z10, Z01 and Z11, respectively. Thus, the pixel value b ofthe interpolated pixel B may be obtained as follows:b=(Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11)/(Z 00+Z 10+Z 01+Z 11).

Since the sum of the pixel values of the reference pixels(Z00+Z10+Z01+Z11) is 1, the above equation can be further simplified to:b=Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11.

In the example shown in FIG. 2, if the twelfth method is selected, thepixel values a00, a10, a01, and a11 are weighted with the weightingfactors Z00, Z10, Z01 and Z11, respectively. Thus, the pixel value b ofthe interpolated pixel B may be obtained as follows:b=(Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11)/(Z 00+Z 10+Z 01+Z 11).

Using the sixteenth method, smoothness and sharpness of an image may becontrolled according to local image characteristics, as shown in FIGS.25A to 25D. The original image shown in FIG. 25A has an upper portionhaving a picture image, and a bottom portion having diagonal lines andcharacters. If the original image of FIG. 25A is interpolated using thelinear method as illustrated in FIG. 25B, the bottom portion of theimage suffers from blurring and jaggedness. If the original image ofFIG. 25A is interpolated using the twelfth method as illustrated in FIG.25C, the upper portion of the image suffers from jaggedness. Bycombining the linear method and the twelfth method, the sixteenth methodcan generate the image having an upper portion that is smooth, and abottom portion that is sharp, as illustrated in FIG. 25D.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 19 are shared by the linear method and the twelfth method, thusincreasing the overall processing speed.

Referring now to FIGS. 2 and 20, an operation for determining a pixelvalue of an interpolated pixel using a seventeenth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the seventeenth method shown in FIG. 20 issubstantially similar to the operation using the seventeenth methodshown in FIG. 19. The differences include replacement of Step S1105 withStep S1205.

Step S1205 determines whether the pixel value of each of the referencepixels is equal to either the maximum value MAX and the minimum valueMIN of the reference pixels. If the pixel value of the reference pixelis equal to the maximum value MAX or the minimum value MIN (“YES” inStep S1205), the operation proceeds to Step S105. Otherwise (“NO” inStep S1205), the operation proceeds to Step S1107.

In this exemplary embodiment, if the pixel value of each of thereference pixels is equal to either the maximum value MAX and theminimum value MIN, the resolution converter 5 assumes that the originalimage, or at least the portion having the reference pixels, is a binaryimage. Based on this characteristic, the twelfth method is selected,which is suitable for enhancing sharpness of the image.

In this exemplary embodiment, if the pixel value of each of thereference pixels is not equal to either one of the maximum value MAX andthe minimum value MIN, the resolution converter 5 assumes that theoriginal image, or at least the portion having the reference pixels, isa multivalue image. Based on this characteristic, the linear method isselected, which is suitable for enhancing smoothness of the image.

Using the seventeenth method, smoothness and sharpness of an image maybe controlled according to local image characteristics, as shown inFIGS. 25A, 25B, 25C, and 25E. By combining the linear method (FIG. 25B)and the twelfth method (FIG. 25C), the seventeenth method can generatethe image having an upper portion that is smooth, and a bottom portionthat is sharp, as illustrated in FIG. 25E.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 20 are shared by the linear method and the twelfth method, thusincreasing an overall processing speed.

Referring now to FIGS. 2 and 21, an operation for determining a pixelvalue of an interpolated pixel using a eighteenth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the eighteenth method shown in FIG. 21 issubstantially similar to the operation using the sixteenth method shownin FIG. 19. The differences include the addition of Step S1304, andreplacement of Step S1105 with Step S1305.

Step S1304 defines a selection range, which may be used for selecting aninterpolation method suitable for processing the specified interpolatedpixel. The selection range may be defined based on a predeterminedconstant M2. The predetermined constant M2 may be any value, however, inthis exemplary embodiment, the predetermined constant M2 is definedbased on the difference value M as illustrated in the followingequation: M2=M/S, wherein S is any value larger than 2. Based on thepredetermined constant M2, the selection range may be defined as a rangethat is larger than (MAX−M2) or smaller than (MIN+M2). The value MAX andthe value MIN correspond to the maximum value and the minimum value ofthe reference pixels.

Step S1305 determines whether the pixel value of each of the referencepixels is within the selection range defined in Step S1304. If the pixelvalue of the reference pixel is within the selection range (“YES” inStep S1305), the operation proceeds to Step S105. If the pixel value ofthe reference pixel is out of the selection range (“NO” in Step S1305),the operation proceeds to Step S1107.

In this exemplary embodiment, if the pixel value of each of thereference pixels is within the selection range, the resolution converter5 assumes that the original image, or at least the portion having thereference pixels, is an image having small variations in pixel valuessuch as a gradation image. Based on this characteristic, the twelfthmethod is selected, which is suitable for enhancing sharpness of theimage.

In this exemplary embodiment, if the pixel value of each of thereference pixels is out of the selection range, the resolution converter5 assumes that the original image, or at least the portion having thereference pixels, is a multivalue image, or an image having largevariations in pixel values. Based on these characteristics, the linearmethod is selected, which is suitable for enhancing smoothness of theimage.

Using the eighteenth method, smoothness and sharpness of an image may becontrolled according to local image characteristics, as shown in FIGS.25A, 25B, 25C and 25F. By combining the linear method (FIG. 25B) and thetwelfth method (FIG. 25C), the eighteenth method can generate the imagehaving the upper portion that is smooth, and the bottom portion that issharp, as illustrated in FIG. 25F. To generate the image shown in FIG.25F, the value S is set to 8, and the value n is set to 3, respectively.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 21 are shared by the linear method and the twelfth method, thusincreasing an overall processing speed.

Referring now to FIGS. 2 and 22, an operation for determining a pixelvalue of an interpolated pixel using a nineteenth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the nineteenth method shown in FIG. 22 issubstantially similar to the operation using the seventeenth method inFIG. 19. The differences include the replacement of Step S1105 with StepS1115, and replacement of Step S1107 with Step S106. Further, the orderof the steps illustrated in FIG. 22 differs from the order of the stepsillustrated in FIG. 19.

Step S1115 determines whether the difference value M obtained in StepS103 is equal to or larger than a predetermined selection value. If thedifference value M is smaller than the selection value (“NO” in StepS1115), the operation proceeds to Step S106. If the difference value Mis equal to or larger than the predetermined selection value (“YES” inStep S1115), the operation proceeds to Step S906.

As described with reference to FIG. 3, the difference value M indicatesa difference between a maximum value MAX and a minimum value MIN of thereference pixels. In this exemplary embodiment, the selection valuecorresponds to any pixel value between 0 and 255, which may be used forselecting an interpolation method suitable for processing the specifiedinterpolated pixel. For example, the selection value may be set to thepixel value of 128. Further, in this exemplary embodiment, theresolution converter 5 is assumed to select either one of theinterpolation methods including the twelfth method and the second methodof the present invention. However, the resolution converter 5 is capableof selecting at least one of the interpolation methods, including anyone of the methods of the present invention and the known methods.

As described above, if the difference value M of the reference pixels issmaller than the selection value, the resolution converter 5 assumesthat variations in pixel values of the reference pixels are relativelysmall. Based on this characteristic, the second method is selected,which is suitable for enhancing smoothness of the image.

If the difference value M of the reference pixels is equal to or largerthan the selection value, the resolution converter 5 assumes thatvariations in pixel values of the reference pixels are relatively large.Based on this characteristic, the twelfth method is selected, which issuitable for enhancing sharpness of the image.

Step S106 obtains a weighting factor for each of the reference pixelsusing the second method. In the example shown in FIG. 2, weightingfactors Z00, Z10, Z01, and Z11 for the reference pixels A00, A10, A01,and A11 are obtained, respectively, as follows:Z 00=x 2*y 2*(1−|a 00−AVE|/M);Z 10=x 1*y 2*(1−|a 10−AVE|/M);Z 01=x 2*y 1*(1−|a 01−AVE|/M); andZ 11=x 1*y 1*(1−|a 11−AVE|/M).

Step S107 calculates a pixel value of the interpolated pixel using thepixel values of the reference pixels. In this exemplary embodiment, eachof the pixel values is weighted with the corresponding weighting factorobtained in Step S906 or S106.

In the example shown in FIG. 2, the pixel values a00, a10, a01, and a11are weighted with the weighting factors Z00, Z10, Z01 and Z11,respectively. Thus, the pixel value b of the interpolated pixel B may beobtained as follows:b=(Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11)/(Z 00+Z 10+Z 01+Z 11).

Using the nineteenth method, smoothness and sharpness of an image may becontrolled according to local image characteristics, as shown in FIGS.25A, 25C, 25G, 25H, 25K and 25L. The original image shown in FIG. 25Ahas an upper portion having a picture image, and a bottom portion havingdiagonal lines and characters. If the original image of FIG. 25A isinterpolated using the second method as illustrated in FIG. 25G,smoothness and sharpness of the image may be enhanced as compared to theimage generated using the method disclosed in the '900 patent shown inFIG. 25K or the image generated using the cubic convolution method shownin FIG. 25L. However, the image of FIG. 25G may still suffer fromblurring and jaggedness in the bottom portion. If the original image ofFIG. 25A is interpolated using the twelfth method as illustrated in FIG.25C, the upper portion of the image suffers from jaggedness. Bycombining the second method (FIG. 25G) and the twelfth method (FIG.25C), the nineteenth method can generate the image having an upperportion that is smooth, and a bottom portion that is sharp, asillustrated in FIG. 25H.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 22 are shared by the second method and the twelfth method, thusincreasing an overall processing speed.

Referring now to FIGS. 2 and 23, an operation for determining a pixelvalue of an interpolated pixel using a twentieth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the twentieth method shown in FIG. 23 issubstantially similar to the operation using the seventeenth methodshown in FIG. 20. The differences include replacement of Step S1205 withStep S1215, and replacement of Step S1107 with Step S106. Further, theorder of the steps illustrated in FIG. 23 differs from the order of thesteps illustrated in FIG. 20.

Step S1215 determines whether the pixel value of each of the referencepixels is equal to either the maximum value MAX and the minimum valueMIN of the reference pixels. If the pixel value of the reference pixelis equal to the maximum value MAX or the minimum value MIN (“YES” inStep S1215), the operation proceeds to Step S906. Otherwise (“NO” inStep S1215), the operation proceeds to Step S106.

In this exemplary embodiment, if the pixel value of each of thereference pixels is equal to either the maximum value MAX and theminimum value MIN, the resolution converter 5 assumes that the originalimage, or at least the portion having the reference pixels, is a binaryimage. Based on this characteristic, the twelfth method is selected,which is suitable for enhancing sharpness of the image.

In this exemplary embodiment, if the pixel value of each of thereference pixels is not equal to either the maximum value MAX and theminimum value MIN, the resolution converter 5 assumes that the originalimage, or at least the portion having the reference pixels, is amultivalue image. Based on this characteristic, the second method isselected, which is suitable for enhancing smoothness of the image.

Using the twentieth method, smoothness and sharpness of an image may becontrolled according to local image characteristics, as shown in FIGS.25A, 25C, 25G, and 25I. By combining the second method (FIG. 25G) andthe twelfth method (FIG. 25C), the twentieth method can generate theimage having an upper portion that is smooth, and a bottom portion thatis sharp, as illustrated in FIG. 25I.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 23 are shared by the second method and the twelfth method, thusincreasing the overall processing speed.

Referring now to FIGS. 2 and 24, an operation for determining a pixelvalue of an interpolated pixel using a twenty-first method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the twenty-first method shown in FIG. 24 issubstantially similar to the operation using the eighteenth method shownin FIG. 21. The differences include replacement of Step S1305 with StepS1315, and replacement of S1107 with Step S106. Further, the order ofthe steps illustrated in FIG. 24 differs from the order of the stepsillustrated in FIG. 21.

Step S1315 determines whether the pixel value of each of the referencepixels is within the selection range defined in Step S1304. If the pixelvalue of the reference pixel is within the selection range (“YES” inStep S1315), the operation proceeds to Step S906. If the pixel value ofthe reference pixel is out of the selection range (“NO” in Step S1315),the operation proceeds to Step S106.

In this exemplary embodiment, if the pixel value of each of thereference pixels is within the selection range, the resolution converter5 assumes that the original image, or at least the portion having thereference pixels, is an image having small variations in pixel values,such as a gradation image. Based on this characteristic, the twelfthmethod is selected, which is suitable for enhancing sharpness of theimage.

In this exemplary embodiment, if the pixel value of each of thereference pixels is out of the selection range, the resolution converter5 assumes that the original image, or at least the portion having thereference pixels, is a multivalue image, or an image having largevariations in pixel values. Based on this characteristic, the secondmethod is selected, which is suitable for enhancing smoothness of theimage.

Using the twenty-first method, smoothness and sharpness of an image maybe controlled according to local image characteristics, as shown inFIGS. 25A, 25C, 25G, and 25J. By combining the second method (FIG. 25G)and the twelfth method (FIG. 25C), the twenty-first method can generatethe image having an upper portion that is smooth, and a bottom portionthat is sharp, as illustrated in FIG. 25J. To generate the image shownin FIG. 25J, the value S is set to 8, and the value n is set to 3.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 23 are shared by the second method and the twelfth method, thusincreasing an overall processing speed.

As described above referring to any one of the sixteenth to twenty-firstmethods, the resolution converter 5 is capable of controlling sharpnessand smoothness of an image. In another example, the resolution converter5 may control information regarding pixel values of an original image,which may be used for determining a pixel value of an interpolatedpixel.

Referring now to FIGS. 2 and 27, an operation for determining a pixelvalue of an interpolated pixel using a twenty-second method is explainedaccording to an exemplary embodiment of the present invention.

Step S100 specifies one of the interpolated pixels. For example, asshown in FIG. 2, the resolution converter 5 specifies an interpolatedpixel B.

Step S101 selects one or more reference pixels, which are originallyprovided in the image data 1, from a vicinity of the specifiedinterpolated pixel. Step S101 further obtains a distance value for eachof the reference pixels. Thus, in the example shown in FIG. 2, theresolution converter 5 selects first to fourth reference pixels A00,A01, A10, and A11, from a vicinity of the interpolated pixel B. For thereference pixels A00 to A11, the resolution converter 5 obtains distancevalues expressed in X and Y coordinate values, (x1, y1), (x1, y2), (x2,y1), and (x2, y2). In the example shown in FIG. 2, four reference pixelsare selected, however, any number of reference pixels may be selected.

Step S102 obtains a pixel value for each of the reference pixelsobtained in Step S101. In the example shown in FIG. 2, the firstreference pixel A00 has a pixel value a00. The second reference pixelA01 has a pixel value a01. The third reference pixel A10 has a pixelvalue a10. The fourth reference pixel A11 has a pixel value a11.

Step S1401 obtains a distance value for each of the reference pixels,which is different from the distance value obtained in Step S101. Inthis exemplary embodiment, the resolution converter 5 calculates adirect distance value L, which is a direct distance between theinterpolated pixel and each of the reference pixels, based on thedistance values expressed in X and Y coordinates. As shown in FIG. 26,the first reference pixel A00 has a direct distance value L00=(x1*y1).The second reference pixel A01 has a direct distance value L01=(x2*y1).The third reference pixel A10 has a direct distance value L10=(x1*y2).The fourth reference pixel A11 has a direct distance value L11=(x2*y2).

Step S1404 determines whether a pixel value of a nearest reference pixelis equal to a pixel value of at least one of adjacent reference pixels.If the pixel value of the nearest reference pixel is equal to the pixelvalue of any one of the adjacent reference pixels (“YES” in Step S1404),the operation proceeds to Step S1408. Otherwise (“NO” in Step S1404),the operation proceeds to Step S1402.

In this exemplary embodiment, the nearest reference pixel corresponds toone of the reference pixels having the smallest direct distance value L.The adjacent reference pixel corresponds to one of the reference pixelsadjacent to the specified interpolated pixel in the direction of the Xor Y axis.

If the pixel value of the nearest reference pixel is equal to the pixelvalue of any one of the adjacent reference pixels, the resolutionconverter 5 assumes that the reference pixels have the same or closervalues, and further assumes that a portion having the reference pixelscorresponds to a portion of a character or a symbol in the image data 1,for example. Based on these characteristics, the nearest neighbor methodis selected, which is suitable for keeping pixel information of theoriginal image.

If the pixel value of the nearest reference pixel is not equal to thepixel value of any one of the adjacent reference pixels, the resolutionconverter 5 assumes that the reference pixels have different pixelvalues, and further assumes that a portion having the reference pixelscorresponds to a portion of a picture image or a diagonal line, forexample. Based on these characteristics, the second method or any othermethod of the present invention is selected, which is suitable forenhancing smoothness of the image.

Step S1408 uses the pixel value of the nearest reference pixel as apixel value of the interpolated pixel. In the example shown in FIG. 2,the pixel value a11 of the fourth reference pixel A11 may be used, ifthe pixel value a1 1 is not equal to any one of the pixel values a01 anda10 of the adjacent reference pixels A01 and A10.

Step S1402 obtains a maximum value MAX and a minimum value MIN of thereference pixels. The maximum value MAX corresponds to a pixel value ofthe reference pixel having the largest pixel value. The minimum valueMIN corresponds to a pixel value of the reference pixel having thesmallest pixel value.

Step S1403 obtains a difference value M1 of the reference pixels basedon the maximum value MAX and the minimum value MIN. In this exemplaryembodiment, the difference value M1 may be expressed by the equation:M1=MAX−MIN+α, with α is any value larger than 0.

Step S105 calculates an average value AVE, which is the average of thepixel values of the reference pixels. In the example shown in FIG. 2,the average value AVE of the reference pixels A00, A10, A01, and A11 canbe calculated as follows:AVE=(a 00+a 01+a 10+a 11)/4.

Step S1406 obtains a weighting factor for each of the reference pixelsusing the pixel values obtained in Step S102, the direct distance valuesL obtained in Step S1401, the average value AVE obtained in Step S105,and a normalization factor. In this exemplary embodiment, the differencevalue M1 obtained in Step S1403 is used as the normalization factor.

In the example shown in FIG. 2, weighting factors Z00, Z10, Z01, and Z11for the reference pixels A00, A10, A01, and A11 are obtained,respectively, as follows:Z 00=L 11*(1−|a 00−AVE|/M 1);Z 10=L 01*(1−|a 10−AVE|/M 1);Z 01=L 10*(1−|a 01−AVE|/M 1); andZ 11=L 00*(1−|a 11−AVE|/M 1).

As shown in the above equations, in this exemplary embodiment, StepS1406 uses the second method described referring to FIG. 3. However, anyone of the above-described and other methods of the present inventionmay be used, as long as it is suitable for enhancing smoothness of animage.

Step S107 calculates a pixel value of the interpolated pixel using thepixel values of the reference pixels. In this exemplary embodiment, eachof the pixel values is weighted with the corresponding weighting factorobtained in Step S1406.

In the example shown in FIG. 2, the pixel values a00, a10, a01, and a11are weighted with the weighting factors Z00, Z10, Z01 and Z11,respectively. Thus, the pixel value b of the interpolated pixel B may beobtained as follows:b=a 00*Z 00/(Z 00+Z 10+Z 01+Z 11)+a 10*Z 10/(Z 00+Z 10+Z 01+Z 11)+a 01*Z01/(Z 00+Z 10+Z 01+Z 11)+a 11*Z 11/(Z 00+Z 10+Z 01+Z 11).

The above equation can be simplified to:b=(Z 00*a 00+Z 10*a 10+Z 01*a 01+Z 11*a 11)/(Z 00+Z 10+Z 01+Z 11).

Step S109 determines whether all interpolated pixels in the image data 1have been processed. If all interpolated pixels have been processed(“YES” in Step S109), the operation ends to store the processed imagedata 1 in the output data storage 7 to be displayed by the displaydevice 10. If all interpolated pixels have not been processed (“NO” inStep S109), the operation returns to Step S100 to specify anotherinterpolated pixel.

Using the twenty-second method, smoothness and information regardingpixel values of an original image may be controlled according to localimage characteristics, as shown in FIGS. 31A, 31B, and 31C. Any one ofthe images shown in FIGS. 31A, 31B, and 31C is generated based on theoriginal image of FIG. 25A. The image shown in FIG. 31A, which isgenerated using the nearest neighbor method, is effective for keepinginformation regarding pixel values of the original image. However, theimage of FIG. 31A suffers from jaggedness, due to the enhanced noisecomponent. The image shown in FIG. 31B, which is generated using thesecond method of the present invention is effective for enhancingsmoothness of the image. However, the image of FIG. 31B suffers from theblurred image. By combining the nearest neighbor method (FIG. 31A) andthe second method (FIG. 31B), the twenty-second method can generate theimage having an upper portion that is smooth, and a bottom portion thatis sharp, as illustrated in FIG. 31C.

In this exemplary embodiment, Step S1404 determines whether the nearestreference pixel has a pixel value equal to a pixel value of any one ofthe adjacent reference pixels. Alternatively, Step S1404 may determinewhether a reference pixel diagonally opposite to the nearest referencepixel has a pixel value equal to a pixel value of any one of theadjacent reference pixels.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 27 are shared by the second method and the nearest neighbor method,thus increasing the overall processing speed.

Referring now to FIGS. 2 and 28, an operation for determining a pixelvalue of an interpolated pixel using a twenty-third method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the twenty-third method shown in FIG. 28 issubstantially similar to the operation using the twenty-second methodshown in FIG. 27. The differences include the addition of Step S1503,and replacement of Step S1404 with Step S1504.

Step S1503 defines a selection range, which may be used for selecting aninterpolation method suitable for processing the specified interpolatedpixel. The selection range may be defined based on the pixel value ofthe nearest reference pixel. For example, referring to FIG. 2, if thefourth pixel value a11 corresponds to the nearest pixel value, theselection range may be defined as a range between (a11+β) and (a11−γ).The value β is any value larger than the pixel value a11. The value γ isany value smaller than the pixel value a11. Preferably, the sum ofvalues β and γ is smaller than 50% of the maximum value of the referencepixels.

Step S1504 determines whether a pixel value of any one of the adjacentreference pixels is within the selection range defined in Step S1503. Inthe example shown in FIG. 2, the second and third reference pixels A01and A10 correspond to the adjacent reference pixels of the interpolatedpixel B. The resolution converter 5 determines whether each of the pixelvalues a01 and a10 is within the selection range. If the pixel value ofthe adjacent pixel is within the selection range (“YES” in Step S1504),the operation proceeds to Step S1408. Otherwise (“NO” in Step S1504),the operation proceeds to Step S1402.

Using the twenty-third method, smoothness and information regardingpixel values of an original image may be controlled according to localimage characteristics, as shown in FIGS. 31A, 31B, and 31D. By combiningthe nearest neighbor method (FIG. 31A) and the second method (FIG. 31B),the twenty-third method can generate the image having an upper portionthat is smooth, and a bottom portion that is sharp, as illustrated inFIG. 31D.

The twenty-third method can enhance sharpness of an image, especiallywhen the image has gradation, as illustrated in FIGS. 32A, 32B, and 32C.If an original gradation image of FIG. 32A is interpolated using thetwenty-second method as illustrated in FIG. 32B, sharpness of the imagemay not be greatly enhanced. If the original gradation image of FIG. 32Ais interpolated using the twenty-third method as illustrated in FIG.32C, sharpness of the image may be enhanced, at least when compared tothe image of FIG. 32B.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 28 are shared by the second method and the nearest neighbor method,thus increasing the overall processing speed.

Referring now to FIGS. 2 and 29, an operation for determining a pixelvalue of an interpolated pixel using a twenty-fourth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the twenty-fourth method shown in FIG. 29 issubstantially similar to the operation using the twenty-third methodshown in FIG. 28. The differences include the addition of Step S1602,replacement of Step S1503 with S1063, and replacement of Step S1504 withStep S1604. Further, the order of the steps illustrated in FIG. 29 maydiffer from the order of the steps illustrated in FIG. 28.

Step S1602 obtains a difference value M using a maximum value MAX and aminimum value MIN of the reference pixels. Alternatively, Step S1602 mayobtain a difference value M, by comparing the pixel value of the nearestreference pixel with the pixel value of the reference pixels other thanthe nearest reference pixel. For example, in the example shown in FIG.2, the difference between the pixel value a11 and the pixel value a10(|a11−a10|), the difference between the pixel value a11 and the pixelvalue a10 (|a11−a10|), and the difference between the pixel value a11and the pixel value a00 (|a11−a00|) may be obtained, respectively. Themaximum value of the obtained differences is used as the differencevalue M.

Step 1603 defines a selection range. The selection range may be definedby a first constant M3 and a second constant M4. The first constant M3may be any value, however, in this exemplary embodiment, the firstconstant M3 is determined based on the difference value M as illustratedin the following equation: M3=M/E, wherein E is any value equal to orlarger than 2. The second constant M4 may be any value, however, in thisexemplary embodiment, the second constant M4 is determined based on thedifference value M as illustrated in the following equation: M4=M/F,wherein F is any value equal to or larger than 2. Based on the firstconstant M3 and the second constant M4, the selection range may bedefined as a range that is equal to or larger than (a1+M3) or equal toor smaller than (a1−M4). The value al corresponds to the pixel value ofthe nearest reference pixel.

Step S1604 determines whether the pixel value of any one of the adjacentreference pixels is within the selection range defined in Step S1603. Ifthe pixel value of the adjacent reference pixel is within the selectionrange (“YES” in Step S1604), the operation proceeds to Step S1408. Ifthe pixel value of the adjacent reference pixel is out of the selectionrange (“NO” in Step S1604), the operation proceeds to Step S1403.

In this exemplary embodiment, if the pixel value of any one of theadjacent reference pixels is within the selection range, the resolutionconverter 5 assumes that the original image, or at least the portionhaving the reference pixels, is an image having small variations inpixel values such as a gradation image. Based on this characteristic,the nearest neighbor method is selected, which is suitable for keepinginformation regarding pixel values of an original image.

In this exemplary embodiment, if the pixel value of any one of theadjacent reference pixels is out of the selection range, the resolutionconverter 5 assumes that the original image, or at least the portionhaving the reference pixels, is a multivalue image, or an image havinglarge variations in pixel values. Based on this characteristic, thesecond method or any other method is selected, which is suitable forenhancing smoothness of the image.

Using the twenty-fourth method, smoothness and information regardingpixel values of an original image may be controlled according to localimage characteristics.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 29 are shared by the second method and the nearest neighbor method,thus increasing the overall processing speed.

Referring now to FIGS. 2 and 30, an operation-for determining a pixelvalue of an interpolated pixel using a twenty-fifth method is explainedaccording to an exemplary embodiment of the present invention.

The operation using the twenty-fifth method shown in FIG. 30 issubstantially similar to the operation using the twenty-fourth methodshown in FIG. 29. The differences include the addition of Step S1404.

Using the twenty-fifth method, smoothness and information regardingpixel values of an original image may be controlled according to localimage characteristics.

Further, in this exemplary embodiment, most of the steps illustrated inFIG. 30 are shared by the second method and the nearest neighbor method,thus increasing an overall processing speed.

In addition to the above-described methods including the sixteenth totwenty-fifth methods, the resolution converter 5 may perform any otherinterpolation method according to the scope of this disclosure andappended claims. For example, elements, features, or functions of theabove-described methods may be combined with each other and/orsubstituted for each other within the scope of this disclosure andappended claims.

Numerous additional modifications and variations are possible in lightof the above teachings. It is therefore to be understood that within thescope of the appended claims, the disclosure of this patentspecification may be practiced in ways other than those specificallydescribed herein.

For example, any one of the above-described and other methods of thepresent invention may be embodied in the form of a computer program. Inone example, the image processing device 9 may be implemented as one ormore conventional general purpose microprocessors and/or signalprocessors capable of performing at least one of the above-described andother methods of the present invention, according to one or moreinstructions obtained from any kind of storage medium. Examples ofstorage mediums include, but are not limited to, flexible disk, harddisk, optical discs, magneto-optical discs, magnetic tapes, involatilememory cards, ROM (read-only-memory), etc.

Alternatively, the present invention may be implemented by ASIC,prepared by interconnecting an appropriate network of conventionalcomponent circuits or by a combination thereof with one or moreconventional general purpose microprocessors and/or signal processorsprogrammed accordingly.

1. A method of converting resolution of an image, comprising the stepsof: specifying an interpolated pixel to be added to the image; selectinga plurality of reference pixels from a vicinity of the interpolatedpixel; obtaining a distance value for each of the reference pixels;extracting a pixel value for each of the reference pixels; generating aweighting factor for a target reference pixel selected from theplurality of reference pixels using the distance value and the pixelvalue of the target reference pixel; and adding, to the image, theinterpolated pixel having a pixel value determined by the weightingfactor of the target reference pixel.
 2. The method of claim 1, furthercomprising the step of: displaying the image to which the interpolatedpixel is added.
 3. The method of claim 1, wherein the generating stepcomprises the step of: calculating, for the target reference pixel, apixel value difference between the pixel value of the target referencepixel and a first predetermined value.
 4. The method of claim 3, whereinthe generating step further comprises the step of: normalizing the pixelvalue difference with a normalization factor.
 5. The method of claim 3,wherein the first predetermined value includes an average of the pixelvalues of the reference pixels.
 6. The method of claim 3, wherein thefirst predetermined value includes an average of the pixel value of thetarget reference pixel and the pixel value of the reference pixelopposing to the target reference pixel.
 7. The method of claim 3,wherein the first predetermined value includes the pixel value of thereference pixel diagonally opposing to the target reference pixel. 8.The method of claim 4, wherein the normalization factor is equal to orlarger than a maximum pixel value of the image.
 9. The method of claim4, wherein the normalization factor is determined by the pixel values ofthe reference pixels.
 10. The method of claim 4, wherein thenormalization factor is determined by a difference value of thereference pixels, indicating a difference between a maximum value and aminimum value of the reference pixels.
 11. The method of claim 4,wherein the normalization factor is determined by at least one of amaximum value and a minimum value of the reference pixels.
 12. Themethod of claim 1, wherein the generating step comprises the step of:obtaining a multiplied weighting factor by raising at least one of thedistance value and the pixel value to the power of a multiplicationvalue, wherein the obtained multiplied weighting factor is used as theweighting factor in the adding step.
 13. The method of claim 1, whereinthe target reference pixel corresponds to all of the reference pixelsselected by the selected step.
 14. The method of claim 1, wherein thetarget reference pixel corresponds to all of the reference pixels, otherthan a nearest reference pixel, selected by the selected step.
 15. Themethod of claim 14, further comprising the step of: generating aweighting factor for the nearest reference pixel using the distancevalue of the nearest reference pixel, wherein the pixel value of theinterpolated pixel is determined further by the weighting factor of thenearest reference pixel.
 16. An image processing device, comprising:means for detecting an input resolution and an output resolution of animage; means for comparing the input resolution with the outputresolution to generate a comparison result; and means for converting theinput resolution to the output resolution based on the comparison resultusing at least one of a plurality of interpolation methods including afirst interpolation method, the first interpolation method comprisingthe steps of: specifying an interpolated pixel to be added to the image;selecting a plurality of reference pixels from a vicinity of theinterpolated pixel; obtaining a distance value for each of the referencepixels; extracting a pixel value for each of the reference pixels;generating a weighting factor for a target reference pixel selected fromthe plurality of reference pixels using the distance value and the pixelvalue of the target reference pixel; and adding, to the image, theinterpolated pixel having a pixel value determined by the weightingfactor of the target reference pixel.
 17. The device of claim 16,wherein the generating step of the first interpolation method comprisesthe steps of: calculating, for the target reference pixel, a pixel valuedifference between the pixel value of the target reference pixel and afirst predetermined value; and normalizing the pixel value differencewith a normalization factor.
 18. The device of claim 17, wherein thegenerating step of the first interpolation method further comprises thestep of: obtaining a multiplied weighting factor by raising at least oneof the distance value and the normalized pixel value difference to thepower of a multiplication value, wherein the obtained multipliedweighting factor is used as the weighting factor in the adding step ofthe first interpolation method.
 19. The device of claim 17, wherein atleast one the first predetermined value and the normalization factor isdetermined based on characteristics of the image.
 20. The device ofclaim 17, wherein at least one the first predetermined value and thenormalization factor is determined based on a user's preference.
 21. Thedevice of claim 18, wherein at least one the first predetermined value,the normalization factor, and the multiplication value is determinedbased on characteristics of the image.
 22. The device of claim 18,wherein at least one the first predetermined value, the normalizationfactor, and the multiplication value is determined based on a user'spreference.
 23. The device of claim 19, wherein the characteristics ofthe image are determined based on the pixel values of the referencepixels.
 24. The device of claim 19, wherein the characteristics of theimage are determined based on a difference value of the referencepixels.
 25. The device of claim 19, wherein the characteristics of theimage are determined based on a maximum value and a minimum value of thereference pixels.
 26. The device of claim 21, wherein thecharacteristics of the image are determined based on the pixel values ofthe reference pixels.
 27. The device of claim 21, wherein thecharacteristics of the image are determined based on a difference valueof the reference pixels.
 28. The device of claim 21, wherein thecharacteristics of the image are determined based on a maximum value anda minimum value of the reference pixels.
 29. The device of claim 16,further comprising: means for obtaining coordinate systems correspondingto the input resolution and the output resolution to be used by theconverting means.
 30. The device of claim 16, further comprising: meansfor storing at least one of the distance value and the pixel value. 31.The device of claim 18, further comprising: means for storing data usedby the converting means to obtain the multiplied weighting factor. 32.The device of claim 16, further comprising: means for selecting aninterpolation method according to characteristics of the image from theplurality of interpolation methods.
 33. The device of claim 32, whereinthe characteristics of the image are determined based on the pixelvalues of the reference pixels.
 34. The device of claim 32, wherein thecharacteristics of the image are determined based on at least one of amaximum value and a minimum value of the reference pixels.
 35. Thedevice of claim 32, wherein the characteristics of the image aredetermines based on a difference value of the reference pixels.
 36. Thedevice of claim 32, wherein the characteristics of the image are adetermined based on a pixel value of a nearest reference pixel selectedfrom the reference pixels.
 37. The device of claim 32, wherein thecharacteristics of the image are determined based on a pixel value of areference pixel diagonally opposing to a nearest reference pixel,selected from the reference pixels.
 38. The device of claim 35, whereinthe selected interpolation method, when the difference value equals to0, comprises the step of: adding the interpolated pixel, having a pixelvalue equal to the pixel value of any one of the reference pixels, tothe image.
 39. The device of claim 32, wherein the plurality ofinterpolation methods further includes a linear interpolation method.40. The device of claim 32, wherein the plurality of interpolationmethods further includes a nearest neighbor method.
 41. An image displayapparatus, comprising: an image processing device configured to detectan input resolution of an image, compare the input resolution with anoutput resolution to generate a comparison result, and convert the inputresolution to the output resolution based on the comparison result usingat least one of a plurality of interpolation methods including a firstinterpolation method; and a display device configured to display theconverted image, the first interpolation method comprising the step of:specifying an interpolated pixel to be added to the image; selecting aplurality of reference pixels from a vicinity of the interpolated pixel;obtaining a distance value for each of the reference pixels; extractinga pixel value for each of the reference pixels; generating a weightingfactor for a target reference pixel selected from the plurality ofreference pixels using the distance value and the pixel value of thetarget reference pixel; and adding, to the image, the interpolated pixelhaving a pixel value determined by the weighting factor of the targetreference pixel to generate the converted image.
 42. A computer programproduct stored on a computer readable storage medium for carrying out amethod, when run on an apparatus, the method comprising the steps of:specifying an interpolated pixel to be added to the image; selecting aplurality of reference pixels from a vicinity of the interpolated pixel;obtaining a distance value for each of the reference pixels; extractinga pixel value for each of the reference pixels; generating a weightingfactor for a target reference pixel selected from the plurality ofreference pixels using the distance value and the pixel value of thetarget reference pixel; and adding, to the image, the interpolated pixelhaving a pixel value determined by the weighting factor of the targetreference pixel.
 43. A computer readable medium storing computerinstructions for performing a method, the method comprising the stepsof: specifying an interpolated pixel to be added to the image; selectinga plurality of reference pixels from a vicinity of the interpolatedpixel; obtaining a distance value for each of the reference pixels;extracting a pixel value for each of the reference pixels; generating aweighting factor for a target reference pixel selected from theplurality of reference pixels using the distance value and the pixelvalue of the target reference pixel; and adding, to the image, theinterpolated pixel having a pixel value determined by the weightingfactor of the target reference pixel.